swift - 如何过滤相等的字符串并只得到每个字符串中的一个

Question

我有一个包含组的项目列表，当我打印它们时，它会显示所有项目。

MOVIE: Cartoon Multi Subtitles
MOVIE: Cartoon Multi Subtitles
MOVIE: Cartoon Multi Subtitles
MOVIE: Cartoon Multi Subtitles
MOVIE: Cartoon Multi Subtitles

MOVIE: English
MOVIE: English
MOVIE: English
MOVIE: English
MOVIE: English

我这样试过:

let item = playlist?.objects.map({ $0.group != group })
-> Unable to infer closure type in the current context

这样:

    for group in item! {
        if group.self != group {
            alertController.addAction(UIAlertAction(title: String(group), style: .default) {
                action in
            })
            print(group)
        }
    }

   @IBAction func button(_ sender: Any) {

        let alertController = UIAlertController(title: "", message: "", preferredStyle: .alert)

        let item = playlist?.objects.map({ $0.group != group })

        for group in item! {
            if group.self == group {
                alertController.addAction(UIAlertAction(title: String(group), style: .default) {
                    action in
                })
                print(group)
            }
        }

        alertController.addAction(UIAlertAction(title: "Cancel", style: .cancel))

        self.present(alertController, animated: true, completion: nil)
    }

我要归档的是删除重复的组。

Answer 1

映射组名后，将该数组放入一个集合中以获得唯一的组名。

let uniqueGroups = Set(playlist?.objects.map({ $0.group != group }) ?? [])